Method of and apparatus for welding spring to aperture grill

ABSTRACT

When three or four panel attachment springs 3 are welded to side portions of an aperture grill 1 (or 21), the aperture grill is disposed so that a grill 107 should be opposed to a predetermined reference plane. The springs are disposed by three or four spring positioning means. A posture of the aperture grill 1 (or 21) is adjusted based on measured results of the respective measurement position Z 0  to Z 4  of the grill 107. Positions of spring pins for supporting springs on the spring positioning means are agreed with positions of panel pins provided on a panel. Thereafter, the respective springs are simultaneously welded to the side portions of the aperture grill. Thus, it is possible to precisely weld the springs to side-portion positions of the aperture grill. When the four springs are welded, it is possible to simultaneously weld the four springs by one equipment.

TECHNICAL FIELD

The present invention relates to a method of and an apparatus forwelding a panel attachment spring to an aperture grill forming a colorcathode-ray tube (hereinafter simply referred to as a CRT).

BACKGROUND ART

In a CRT employing an aperture grill as a color selection mechanism foruse in a television receiver and a monitor television receiver of acomputer, an aperture grill with a large number of slits formedtherethrough is attached to an inside of a panel coated on its innersurface with fluorescent paints of three primary colors (R, G, B). Threeprimary color electron beams emitted from an electron gun pass throughthe slits of the aperture grill and are radiated on fluorescent paintportions of corresponding colors on the inner surface of the panel.

The above aperture grill includes a substantially rectangular frameformed of four members of upper, lower, left and right members, and agrill stretched between the upper and lower members. A large number ofthe above-mentioned slits are formed through the grill extendedvertically at portions with intervals from its left and right.

The above panel includes a substantially rectangular panel portioncoated on its inner surface with the above fluorescent paints and fourskirt portions of upper, lower, left and right skirt portions,projectingly formed so as to be extended from four sides of the panelportion toward the inside of the tube. The panel portion is formed so asto have a little larger size as compared with the above grill.

The above aperture grill is attached to the panel by engaging pinapertures of panel attachment springs welded to the three or fourmembers of the aperture grill with pins (so-called panel pins) fitted toinner surfaces of the three or four skirt portions of the panel.

If an interval between a grill surface and the inner surface of thepanel portion is different from a design value in a state that theaperture grill is attached to the panel as described above, then theelectron beams passed through the slits of the grill are not accuratelyradiated on the corresponding fluorescent paint portions of the panelportion, which leads to defects of an assembled CRT such as an erroneouslanding of beams or the like.

Therefore, it is important to accurately set particularly the intervalat any portion between the grill surface and the inner surface of thepanel portion to the design value at any places in a CRT requiring highdefinition such as the monitor television receiver of the computer, aCRT having a large screen size and so on. For this end, it is necessaryto accurately position the pin aperture of the spring relative to thegrill.

In the prior art, there is increased an accuracy of a position where thesprings are welded to the respective members of the above frame.

However, it is sometimes observed that the above frame is twisted bystrains of its respective members or the like. In this case, the grillis twisted similarly to the frame. Accordingly, even if the accuracy ofthe spring welded positions relative to the respective members isincreased, the positions of the pin apertures of the springs relative tothe grill are displaced because of the twisted grill. This positionaldisplacement prevents the interval between the grill surface and theinner surface of the pane portion in the state that the aperture grillis attached to the panel, from deviating from the design value at someplaces. Therefore, defects such as the erroneous landing of the beams orthe like cannot be prevented surely.

Since the springs are welded to the respective members in considerationof only the positional accuracy of the spring relative to each of themembers in the prior art, it is not known before the welding of thesprings whether or not positions of the pins of the respective springsare set to positions where the interval (a so-called grill height GH)between the grill surface and the inner surface of the panel portion inthe state that the aperture grill is attached to the panel is always setto the design value at any place. Only after the springs are welded, itwas possible to confirm the accuracy by measuring the interval betweenthe grill surface and the inner surface of the panel after the aperturegrill was practically attached to the panel.

Accordingly, there tend to be produced a large number of unsatisfactoryaperture grills in which the springs are welded to the member positionswhich cause deviation of the intervals between the grill surface and theinner surface of the panel portions from the design value at someportions. This results in demerit of unsatisfactory yield.

The aperture grill of the high-definition CRT is attached to the panelthrough four springs welded to the four members of the upper, lower,left, and right members. When the four springs are welded, two assemblyaccuracies in an interval GH marriage and an engagement marriage arerequired. The interval GH marriage is to set the interval GH between thepanel and the aperture grill which are to be assembled to the standardsize. The engagement marriage is to agree the positions of the pinapertures of the four springs welded to the aperture grill with thepositions of the four pins provided on the panel.

The four springs have been welded in the following manner. The aperturegrill is positioned with reference to the positions of the three springsof the first, second, and third springs, so that the interval GH shouldbe set to the standard size. The first, second and third springs arewelded. Thus, the interval GH marriage is finished. Subsequently, thepositions of the pins of the panel to be assembled with the aperturegrill are transferred to reference pins provided on a welding machine.The aperture grill is positioned by the first, second and third springs,and then a fourth spring is welded. Thus, the engagement marriage isfinished.

As described above, the prior art employs two spring welding processesfor the interval GH marriage and the engagement marriage. Therefore,requirement of a plurality of equipments leads to unsatisfactoryefficiency in a space of the equipments.

The present invention is proposed in view of such aspects. An object ofthe present invention is to provide a method of and an apparatus forwelding a spring to an aperture grill which allow the spring forattaching the panel to be accurately welded to the side-portionpositions of the aperture grill in correspondence with the respectivegrills so that the electron beams passed through the grill should beaccurately radiated on the corresponding fluorescent paint positions ofthe panel portion in the assembled CRT.

Another object of the present invention is to provide the method of andthe apparatus for welding the spring to the aperture grill which, whenthe four springs are welded to the aperture grill, allow the foursprings to be simultaneously welded by one equipment.

DISCLOSURE OF THE INVENTION

According to the present invention, when panel attachment springs arewelded to at least three side portions of four side portions of asubstantially rectangular aperture grill having a color selection grill,the aperture grill is disposed so that the grill should be opposed to apredetermined reference plane. The springs are disposed at positionsopposed to the at least three side portions outside the aperture grillon an upper plane in parallel to the reference plane. Positions of aplurality of measurement positions of the grill relative to thereference plane are measured. A posture of the aperture grill isadjusted based on measured results of the respective measurementpositions of the grill so that the respective measurement positionsshould be located at predetermined reference positions relative to thereference plane. After the posture of the aperture grill is adjusted,the springs are moved close to the aperture grill on the plane inparallel to the reference plane, brought in contact with theabove-mentioned at least three side portions, and welded to the threeside portions.

Also, according to the present invention, three supporting bodiesrespectively support one side portion of a pair of the above-mentionedside portions opposed to each other at a middle-side portion position inthe extended direction of the above-mentioned side portion and the otherside portion at two side-portion positions located at an interval in theextended direction of the side portions. The respective supportingbodies are moved in the direction in which they are moved close to andaway from the respective side portions. Thus, the posture of theaperture grill is adjusted.

Further, according to the present invention, the measurement of thepositions of a plurality of measurement positions of the grill withrespect to the reference plane and the welding of the springs to the atleast three side portions are respectively carried out at positionslocated at an interval along the reference plane.

Also, according to the present invention, a spring welding apparatus isan apparatus for welding the panel attachment springs to the at leastthree side portions of the four side portions of the substantiallyrectangular aperture grill having the color selection grill, andincludes a table, an aperture-grill supporting means for supporting theaperture grill on the table so that a posture of the aperture grill canbe adjusted, a grill-position measuring means for measuring thepositions of the plurality of measurement positions of the grill in astate that the aperture-grill supporting means supports the aperturegrill, an aperture-grill posture adjusting means for driving theaperture-grill supporting means based on results obtained by measurementof the grill-position measuring means and for adjusting the posture ofthe aperture grill so that the plurality of measurement positions of thegrill should be located at respective predetermined positions, anaperture-grill positioning means for positioning on the table theaperture grill adjusted in posture by the aperture-grill postureadjusting means, a spring positioning means respectively disposed atpositions opposed to the at least three side portions of the aperturegrill positioned by the aperture-grill positioning means, for bringingthe springs in contact with the at least three side portions to positionthe springs, and a spring welding means for welding the springspositioned by the spring positioning means to the side portions of theaperture grill positioned by the aperture-grill positioning means.

Further, according to the present invention, the aperture-grillsupporting means includes three supporting bodies which are provided inthe table so that they can be lifted up and down, for respectivelysupporting one side portion of the above-mentioned side portions whichare opposed to each other, at a middle side-portion position in theextended direction of the side portion and the other side portionslocated at an interval in the extended direction of the side portion atthe two side-portion positions. The aperture-grill posture adjustingmeans includes lifting and driving sources for lifting the respectivesupporting bodies up and down.

Also, according to the present invention, the aperture-grill supportingmeans, the grill-position measuring means, the aperture-grill postureadjusting means, the aperture-grill positioning means, and the springpositioning means are provided in the table.

According to the present invention, there are further provided springsupplying means for supplying the springs to the respective springpositioning means.

According to the present invention, there are further provided a basemount for movably supporting the table and a table drive means formoving the table on the base mount. The measurement of the positions ofthe plurality of measurement positions of the grill by thegrill-position measuring means, the supply of the springs to therespective spring positioning means by the spring supplying means, andthe welding of the springs to the aperture grill by the spring weldingmeans are carried out in a state that the table are moved to differentpositions on the base mount.

According to the present invention, the side portion of the aperturegrill includes four members of upper, lower, left and right members.Spring holders are attached to at least three members of theabove-mentioned four members. The spring welding means welds the springsto the spring holders.

According to the present invention, when the panel attachment springsare welded to four side portions of the substantially rectangularaperture grill having the color selection grill, the springs aredisposed at respective spring pins of the four spring positioning meansfor positioning the springs. The aperture grill is disposed so that thegrill should be opposed to the reference plane determined by the springpins of the three spring positioning means of the four springpositioning means. The positions of the plurality of measurementpositions of the grill relative to the reference plane are measured. Theposture of the aperture grill is adjusted based on the measured resultsof the respective measurement positions of the grill so that therespective measurement positions should be located at the predeterminedreference positions relative to the reference plane. The positions ofthe respective spring pins of the four spring positioning means areagreed with positions of panel pins provided on four side portions of apanel of a cathode-ray tube. The four springs are welded to the fourside portions of the aperture grill simultaneously.

According to the present invention, of the four spring pins, second andthird spring pins opposed to each other in the first direction are movedso that first-direction positions of the second and third spring pinsshould be agreed with positions of second and third panel pins, whichare opposed to each other in the first direction, of the panel pins. Afirst spring pin, which is one of the spring pins opposed to each otherin the second direction perpendicular to the first direction, thereof ismoved so that the first-direction position and second-direction positionof the above-mentioned first spring pin should be agreed with a positionof a first panel pin which is one of panel pins opposed to each other inthe second direction. Further, a fourth spring pin thereof which is theother one of pins opposed to each other in the second direction is movedso that first-, second-, and third-direction positions, which areperpendicular to one another, of the above-mentioned fourth spring pinshould be agreed with a position of a fourth panel pin which is theother one opposed to each other in the second direction,. Thus, thepositions of the above-mentioned four springs are agreed with thepositions of the above-mentioned four panel pins.

According to the present invention, the spring welding apparatus is anapparatus for welding the panel attachment springs to four side portionsof the substantially rectangular aperture grill having the colorselection grill, and includes the table, the aperture-grill supportingmeans for supporting the above-mentioned aperture grill on the table atthree positions so that the posture of the aperture grill can beadjusted, the grill-position measuring means for measuring the positionsof the plurality of measurement positions of the grill in a state thatthe aperture-grill supporting means supports the aperture grill, theaperture-grill posture adjusting means for driving the aperture-grillsupporting means based on results obtained by measurement of thegrill-position measuring means and for adjusting the posture of theaperture grill so that the plurality of measurement positions of thegrill should be located at the respective predetermined positions, theaperture-grill positioning means for positioning on the table theaperture grill adjusted in posture by the aperture-grill postureadjusting means, first, second, third and fourth spring positioningmeans respectively disposed at positions corresponding to the four sideportions of the aperture grill positioned by the aperture-grillpositioning means, for bringing the above-mentioned springs in contactwith the above-mentioned four side portions to position the springs, andthe spring welding means for welding the springs positioned by thespring positioning means to the side portions of the aperture grillpositioned by the aperture-grill positioning means. Of the four springpositioning means, the second and third spring positioning means opposedto each other in the first direction can be moved and adjusted in thefirst direction. The first spring positioning means thereof which is oneof the means opposed to each other in the second direction perpendicularto the first direction can be moved and adjusted in the first and seconddirections. The fourth spring positioning means thereof which is theother one of the means opposed to each other in the second direction canbe moved and adjusted in the first, second and third directionsperpendicular to one another.

According to the present invention, after the posture of the aperturegrill is adjusted so that the respective measurement positions of thegrill relative to the reference plane should be located at thepredetermined reference positions, the springs are welded to the sideportions of the aperture grill. Therefore, even if the grill is twisted,the positions of the pin apertures of the springs relative to therespective measurement positions of the grill are precisely set to thedesign values. The panel attachment springs are precisely welded to theside-portion positions of the aperture grill. Accordingly, the intervalbetween the grill surface and the inner surface of the panel portion isalways set to the precise design value at any place in a state theaperture grill is attached to the panel. Therefore, it is possible toaccurately radiate the electron beams passed through the grill on thecorresponding fluorescent paint positions of the panel in the assembledCRT. It is also possible to reduce the ratio in production of theunsatisfactory aperture grills, which improves the yield.

It is possible to weld the four springs simultaneously. Therefore, anerror in positioning the aperture grill and the springs is reduced,which can improve the quality of the cathode-ray tube. An equipment forthe interval GH marriage and an equipment for the engagement marriagecan be made integral, which can improve an efficiency in a space of theequipment.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of an example of an aperture grill to whichthe present invention is applied from its rear side;

FIG. 2 is a perspective view of a panel to which the aperture grillshown in FIG. 1 is attached from its rear side;

FIG. 3 is a perspective view showing a state in which the aperture grillis attached to the panel;

FIG. 4 is a front view of a welding apparatus according to an embodimentof the present invention;

FIG. 5 is a plan view of a table of the welding apparatus according tothe embodiment of the present invention;

FIG. 6 is a perspective view showing a schematic arrangement of agrill-position measuring means of the welding apparatus according to theembodiment of the present invention;

FIG. 7 is a perspective view of a parting mechanism for engaging andreleasing upper and lower positioning rollers with and from upper andlower lateral members, of the welding apparatus according to theembodiment of the present invention;

FIG. 8 is a diagram showing a schematic arrangement of a springpositioning means of the welding apparatus according to the embodimentof the present invention;

FIG. 9 is an explanatory diagram showing a state that an aperture grillis attached to a panel;

FIG. 10 is a perspective view of another example of the aperture grillto which the present invention is applied from its rear side;

FIG. 11 is a perspective view of a panel to which the aperture grillshown in FIG. 10 is attached from its rear side;

FIG. 12 is a rear view showing a state that the aperture grill isattached to the panel;

FIG. 13 is a cross-sectional view showing a state that the aperturegrill is attached to the panel;

FIG. 14 is a schematic, plan view of a welding apparatus according toanother embodiment of the present invention;

FIG. 15 is a schematic, front view of the welding apparatus according toanother embodiment of the present invention;

FIG. 16 is a plan view of a table of the welding apparatus according toanother embodiment of the present invention;

FIG. 17 is a plan view of an arrangement of an aperture-grillpositioning means of the welding apparatus according to anotherembodiment of the present invention;

FIG. 18 is a side view of a main part of an aperture-grill supportingmeans of the welding apparatus according to another embodiment of thepresent invention;

FIG. 19 is a diagram used to explain an operation of the weldingapparatus according to another embodiment of the present invention; and

FIG. 20 is an explanatory diagram of measurement of a grill position andthe supporting of the aperture grill of the welding apparatus accordingto another embodiment of the present invention.

BEST MODE CARRYING OUT THE INVENTION

An aperture grill to which the present invention is applied and anarrangement of a panel for supporting the aperture grille will initiallybe described.

FIG. 1 is a perspective view of an aperture grill seen from its rearside. An aperture grill 1 includes a substantially rectangular frame 101formed of upper and lower lateral members 103 and left and rightlongitudinal members 105 for respectively jointing both rear-surfaceends of the both lateral members 103, and a sheet-shaped grill 107 whichis stretched between front surfaces of the above upper and lower lateralmembers 103 and through which a plurality of slits 109 extended in theupward and downward are formed at an interval in the left and rightdirection.

Each of the lateral member 103 is curved and formed so as to beprojected forwards at its center portion as compared with its both endportions in the left and right direction. Spring holders 111 are weldedto outer side surfaces of the lower lateral member 103 and the left andright longitudinal members 105. Panel attachment springs 3 are welded toouter surfaces of the respective spring holders 111.

Each of the springs 3 is formed of a middle portion 301, a base portion303 and a head portion 305 both of which are formed projectingly fromboth ends of the middle portion 301, being formed so as to berectangular when it is seen from its front side. The base portion 303 isbent toward an outer surface of the middle portion 301. The head portion305 is bent toward an inner surface of the middle portion 301. A pinaperture 307 is formed through the head portion 305.

FIG. 2 is a perspective view of a panel seen from its rear side. A panel5 includes a substantially rectangular panel portion 501 which has alittle larger size as compared with the grill 107 and is bent and formedso as to correspond to the frame 101, and four skirt portions of upper,lower, left and right skirt portions 503, formed projectingly from foursides of the panel portion 501. Pins (so-called panel pins) 505 capableof being engaged with the pin apertures 307 of the springs 3 are fittedto inner surfaces of the lower, left and right skirt portions 503.

The aperture grill 1 is attached to the panel 5 by welding the baseportions 303 of the springs 303 to the spring holders 111 to engage thepin apertures 307 of the springs 3 with the pins 505 of the panel 5 asshown in FIG. 3. Thus, the aperture grill 1 is supported at the insideof the panel 5.

A welding method according to the present invention together with awelding apparatus according to the present invention will be described.

FIG. 4 is a front view of a welding apparatus according to theembodiment. FIG. 5 is a plan view of a table in the welding apparatus.

A welding apparatus 7 includes a horizontally long base mount 9 having arectangular shape when it is seen from its front side, a table 11movably disposed on the base mount 9 for receiving the aperture grill 1thereon, an aperture-grill supporting means 13 provided on the table 11,grill-position measuring means 15, left and right and upper and loweraperture-grill positioning means 17A, 17B, spring positioning means 19,a spring supplying means 21 provided on the base mount 9 for supplyingthe springs 3 to the spring positioning means 19, a spring welding means23 for welding the springs 3 positioned by the spring positioning means19 on the aperture grill 1, etc.

As shown in FIG. 4, the table 11 is moved by a table drive means, notshown, provided on the base mount 9 in the left and right directionamong a spring supply position 901 located at a position to a right endof the base mount 9, a spring welding position 903 at the left end ofthe base mount 9, and an aperture-grill delivery position 905 located atthe middle of both positions. At the aperture-grill delivery position905, the aperture grill 1 is delivered by a conveying means (not shown)onto the table 11 with the front surface of the grill 107 being facedtoward the table 11.

In the embodiment, an upper surface of the table 11 corresponds to areference plane.

Three aperture-grill supporting means 13 are provided. As shown in FIG.5, each of the aperture-grill supporting means 13 includes a supportingbody 1301 supported by the table 11 so as to be capable of being liftedup and down. Each of the aperture-grill supporting means is arrangedsuch that, in a state that the aperture grill 1 is delivered onto thetable 11, the respective supporting bodies 1301 support the aperturegrill at a substantial middle in the left and right direction of thefront position of the upper lateral member 103 and two front positions,which are located at an interval in the left and right direction, of thelower lateral member 103.

Each of the supporting bodies 1301 is formed of a motor, a ball threadand so on and lifted up and down by a lifting and driving unit (notshown) provided between the table 11 and the supporting body 1301. Thesupporting bodies 1301 are lifted up and down by the lifting and drivingunit under the control of a control means, not shown, (e.g., amicrocomputer) based on a measured result of the grill-positionmeasuring means 15. In the embodiment, the lifting and driving unit andthe control means form an aperture-grill posture adjusting means.

In FIG. 5, reference numeral 1303 depicts a supporting plate combinedwith the supporting body 1301. Reference numeral 1305 depicts a pressarm supported by the supporting plate 1303 so that the base portion 303can be rocked. The press arm 1305 is rocked downward by a rocking anddriving source, not shown, thereby a head portion of the press arm 1305being brought in contact with each of the rear surfaces of the upper andlower lateral members 103. Thus, the lateral member 103 is pressed tothe supporting body 1301.

As shown in FIG. 5, the five grill-position measuring means 15 areprovided with corresponding to a measurement position Z₀ at asubstantial center of the front of the grill 107 of the aperture grill 1supported by the three supporting bodies 1301, and measurement positionsZ₁ to Z₄ located to its four-corner sides.

As shown in FIG. 6, the grill-position measuring means 15 includes asupporting plate 1503 supported through two lifting guides 1501 on thetable 11 side so as to be capable of being lifted up and down, a liftingand driving unit 1505 for lifting the supporting plate 1503 up and down,and a measuring instrument 1507 which is supported by the supportingplate 1503 and has a measuring point 1509 capable of being brought incontact with and away from the grill 107.

The lifting and driving unit 1505 includes a pulse motor 1511 supportedby the table 11 and a ball thread 1513 fitted to the supporting plate1503 and combined with an output shaft of the motor 1511. The measuringinstrument 1507 is formed of a magnetic scale or a micrometer.

The grill-position measuring means 15 is arranged such that height ofthe supporting plate 1503 obtained when it is lifted up and down isadjusted by the lifting and driving unit 1505, the respective measuringpoints 1509 are brought in contact with the five measurement positionsZ₀ to Z₄ of the grill 107 of the aperture grill 1 supported by the threesupporting bodies 1301, thereby the measuring instrument 1507 measuringthe positions of the measurement positions Z₀ to Z₄, and then themeasured results are output to the above control means.

As shown in FIG. 5, the left and right aperture-grill positioning means17A are respectively disposed on outer sides of the left and rightlongitudinal members 105, and the upper and lower aperture-grillpositioning means 17B are respectively disposed on outer sides of theupper and lower lateral members 103.

As shown in FIG. 7, the respective left and right aperture-grillpositioning means 17A include positioning rollers 1701 for being engagedwith and released from substantially middle outer-surface positions inthe upward and downward direction of the left and right longitudinalmembers 105, and sliders 1703 which rotatably support the rollers 1701and are supported by the table 11 through guide rails 1702 so that theycan be moved in the left and right direction.

As shown in FIG. 5, the left and right aperture-grill positioning means17A are arranged such that a parting mechanism 1705 provided between thesliders 1703 of both of the aperture-grill positioning means 17A permitsthe left and right positioning rollers 1701 to be respectively engagedwith and released from the left and right longitudinal members 105 ofthe aperture grill 1 supported by the three supporting bodies 1301 insynchronization with each other.

As shown in FIG. 7, the respective upper and lower aperture-grillpositioning means 17B include two positioning rollers 1707 for beingengaged with and released from two outside positions, which are locatedat an interval in the left and right direction, of the upper and lowermembers 103.

The two respective lower positioning rollers 1707 are rotatablysupported at left and right ends of an arm 1709. The arm 1709 issupported at its substantially middle portion in the left and rightdirection by the table 11 through a slider 1711 and a guide rail 1713 soas to be movable in the upward and downward direction.

The two respective upper positioning rollers 1707 are provided at bothof left and right ends of a rocking arm 1717 which can be rocked arounda supporting shaft 1715. The supporting shaft 1715 is fitted to a slider1719. The slider 1719 is supported by the table 11 through a guide rail1721 so as to be movable in the upward and downward direction.

The upper and lower aperture-grill positioning means 17B are arrangedsuch that a parting mechanism 1723 provided between the sliders 1711,1719 of the both of the aperture-grill positioning means 17B permits theupper and lower positioning rollers 1707 to be engaged with and releasedfrom the upper and lower lateral members 103 of the aperture grill 1supported by the three supporting bodies 1301 in synchronization witheach other, and even if the frame 101 is twisted, the rocking of therocking arm 1717 allows the respective upper and lower positioningrollers 1707 to be reliably engaged with the upper and lower lateralmembers 103, thereby the aperture grill 1 being able to be positioned.

The parting mechanism 1723 is driven by an expanding operation of an aircylinder 1727 combined with one end of a link 1725 of the partingmechanism 1723. The parting mechanism 1707 is driven by the expandingoperation of the air cylinder 1727 through a rotation shaft 1729 fittedto a middle portion of the link 1725 in synchronization with the partingmechanism 1723.

The three spring positioning means 19 are provided. As shown in FIG. 5,the spring positioning means 19 are disposed on the outer sides of thelower lateral member 103 and the left and right longitudinal members 105of the aperture grill 1, respectively.

As shown in FIG. 8, each of the spring positioning means 19 includes amoving block 1901 supported by the table 11 so as to be movable on aplane in parallel to the upper surface of the table 11 in the directionin which the block is moved close to and away from the aperture grill 1,an air cylinder 1903 for moving the moving block 1901, and a holdingmember 1905 provided an the head end of the moving block 1901 opposed tothe aperture grill 1 for holding the spring 3.

The holding member 1905 includes a pin (a so-called spring pin) 1907which can be inserted into the pin aperture 307 of the spring 3, aring-shaped magnet 1909 for being magnetically fitted to an outersurface of the head portion 305 of the spring 3 with the pin 1907 beinginserted into the pin aperture 307, and two projections (not shown)which are engaged with both edges of the head portion 305 to therebyprevent the spring 3 from being rotated. The pins 1907 of the respectivespring positioning means 19 are disposed above the table 11 at positionswhose heights from the table are the same.

The spring positioning means 19 is arranged such that, in a state thatthe holding member 1905 holds the spring 3 and the moving block 1901 isbrought close to the aperture grill 1 by the air cylinder 1903, theinner surface of the base portion 303 of the spring 3 is brought incontact with an outer surface of the spring holder 111 of the aperturegrill 1, and as shown in FIG. 5, the spring 3 is deformed in the samestate obtained when the aperture grill 1 is attached to the panelportion 501.

As shown in FIG. 4, the spring supplying means 21 includes a magazine2101 disposed at the right end of the base mount 9 for housing a largenumber of springs 3, and a supply robot (not shown) for picking up thesprings 3 from the magazine 2101 one by one and supplying them to therespective spring positioning means 19 at the spring supply position 901of the tables 11.

The supply robot includes an arm movably provided between the magazine2101 and each of the spring positioning means 19, a chuck provided atthe tip end of the arm so as to be capable of being opened and closed,and a drive source for moving the arm and for opening and closing thechuck. The supply robot is arranged such that the chuck grips the middleportion 301 of the spring 3 located at a spring pickup slot (not shown)of the magazine 2101 and the spring 3 is delivered to the holding member1905 brought in a state that the moving block 1901 is moved in thedirection in which the moving block is moved away from the aperturegrill 1.

As shown in FIG. 4, the spring welding means 23 includes a supportingframe 2301 provided at the left end of the base mount 9 so as to stand,a welding machine 2303 supported by the supporting frame 2301 so as tobe lifted up and down, and a lifting and driving mechanism (not shown)for lifting the welding machine 2303 up and down. The welding machine2303 includes three welding units (not shown) for the lower lateralmember 103, the left longitudinal member 105, and the right longitudinalmember 105.

Each of the welding units includes two electrode portions disposed so asto be moved close to and away from each other with being opposed to eachother. In a state that the welding machine 2303 is lifted down by thelifting and driving mechanism, the respective electrode portions areopposed to the inner surface of the spring holder 111 and the outersurface of the base portion 303 of the spring 3. The respectiveelectrode portions are brought close to each other to be brought incontact with the spring holder 111 and the spring 3 and then energized,thereby the spring holder 111 and the spring 3 being welded by spotwelding.

It will be described to weld the spring 3 to the spring holder 111 bythe above welding apparatus.

The spring supplying means 21 supplies the spring 3 to each of thespring positioning means 19 at first.

Then, the table drive means moves the table 11 to the aperture-grilldelivery position 905, where the lifting and driving units of theaperture-grill supporting means 13 respectively locate the head ends ofthe three supporting bodies 1301 at the reference positions whoseheights from the table 11 are the same. In this state, the aboveconveying means mounts the aperture grill 1 on the three supportingbodies 1301.

The lifting and driving units 1505 of the grill-position measuring means15 respectively lift the supporting plates 1503 to bring the respectivemeasuring points 1509 of the five measuring instruments 1507 in contactwith the five measurement positions Z₀ to Z₄. The measuring instruments1507 measure the positions of the measurement positions Z₀ to Z₄ basedon the heights of the supporting plates 1503 at this time, respectively.In this embodiment, the respective measuring instruments 1507 measurethe heights from the table 11 to the measurement positions Z₀ to Z₄,respectively.

The above control means compares the respective heights of themeasurement positions Z₀ to Z₄ with predetermined reference valuesindicative of ideal heights of the measurement positions Z₀ to Z₄. Thecontrol means also determines whether or not the heights of the fourmeasurement positions Z₁ to Z₄ to the four-corner sides of the grill 107are equal.

The above predetermined reference values are determined based on heightvalues obtained when, in a state that the head ends of the threesupporting bodies 1301 are located at the reference positions whoseheights from the table 11 are the equal and a master of the aperturegrill 1 precisely manufactured in accordance with the design values ismounted on the three supporting bodies 1301, the measuring instruments1507 measure the heights from the table 11 of the respective measurementpositions Z₀ to Z₄. The positions of the respective measurementpositions Z₀ to Z₄ on the master at this time correspond to thereference positions.

When the heights of the measurement positions Z₀ to Z₄ are deviated fromthe reference values or when the heights of the four measurementpositions Z₁ to Z₄ on the four-corner side of the grill 107 are uneven,the measuring points 1509 are moved away from the respective measurementpositions Z₀ to Z₄. In order to correct differences between the heightsof the respective measurement positions Z₀ to Z₄ and the referencevalues and unevenness of the heights of the four measurement positionsZ₁ to Z₄ on the side of the four corners of the grill 107, the liftingand driving unit is operated under the control of the above controlmeans to lift the respective supporting bodies 1301 up and down, therebythe posture of the aperture grill 1 being adjusted.

If the differences between the heights of the respective measurementpositions Z₀ to Z₄ and the reference values and unevenness of theheights of the four measurement positions Z₁ to Z₄ on the side of thefour corners of the grill 107 have been corrected by adjusting theposture of the aperture grill 1, the measuring points 1509 are movedaway from the respective measurement positions Z₀ to Z₄, and thepositioning rollers 1707, 1701 are engaged with the upper and lowerlateral members 103 and the left and right longitudinal members 105,respectively, thereby the aperture grill 1 being positioned. Thereafter,the table drive means moves the table 11 to the spring supply position901.

The moving blocks 1901 of the spring positioning means 19 are moved inthe directions in which they move close to the aperture grill 1, therebythe base portions 303 of the springs 3 being brought in contact with thespring holders 111.

The table drive means moves the table 11 to the spring welding position903, where the welding machine 2303 of the spring welding means 23 islifted down and the three welding units weld the base portions 303 ofthe springs 3 to the respective spring holders 111. Thereafter, themeasuring instruments 1507 measure the heights of the respectivemeasurement positions Z₀ to Z₄ again.

The welding machine 2303 is lifted up next. The table drive means movesthe table 11 to the aperture-grill delivery position 905. The movingblocks 1901 of the spring positioning means 19 are moved in thedirections in which they are moved away from the aperture grill 1,thereby the pins 1907 being pulled out of the pin apertures 307 of thesprings 3. The positioning rollers 1707, 1701 are respectively movedaway from the upper and lower lateral members 103 and the left and rightlongitudinal members 105, thereby the operation for positioning theaperture grill 1 being released. The above conveying means conveys theaperture grill 1 from the table 11.

According to this embodiment, the three supporting bodies 1301 locatedat the reference positions whose heights from the table 11 are the samerespectively support the upper lateral member 103 of the aperture grill1 delivered to the table 11 by the conveying means at one position andthe lower lateral member 103 thereof at two positions. In this state,the positions of the five measurement positions Z₀ to Z₄ located at thesubstantial center and on the sides of the four corners of the grill 107are measured. In accordance with the measured results, the respectivesupporting bodies 1301 are lifted up or down. The posture of theaperture grill 1 is adjusted so that the heights of the respectivemeasurement positions Z₀ to Z₄ should be agreed with the referencevalues and the four measurement positions Z₁ to Z₄ should be equal.

Therefore, even if the frame 101 and the grill 107 are twisted becauseof the strain of the respective lateral and longitudinal members 103,105 and so on, the springs 3 are reliably supplied and welded to thepositions of the lateral and longitudinal members 103, 105 where thepositions of the respective pin apertures 307 relative to themeasurement positions Z₀ to Z₄ are set to the precise design values.Accordingly, it is always possible to set the interval GH (Grill Height)between the surface of the grill 107 and the inner surface of the panelportion 501 to the precise design values at any place, as shown in FIG.9, in the state that the aperture grill 1 is attached to the panel 5.The electron beams passed through the grill can be radiated on thecorresponding fluorescent paint positions of the panel portion, whichcan reliably prevent the defects of the assembled CRT such as theerroneous landing of the beam or the like. It is possible to reduce aratio in production of the unsatisfactory aperture grill 1 in which thepin aperture 307 is positionally displaced. This reduction can improvethe yield.

According to the embodiment, the table 11 is movably provided on thebase mount 9. The operation of the conveying means for delivering andconveying the aperture grill 1 to and from the table 11, the operationof the spring supplying means 21 for supplying the springs 3 to therespective spring positioning means 21 on the table 11, and theoperation of the spring welding means 23 for welding the springs 3 tothe aperture grill 1 are carried out at the positions which aredifferent from one another on the base mount 9. Therefore, the conveyingmeans, the spring supplying means 21 and the spring welding means 23 cancarry out their works without interfering one another.

Further, according to the embodiment, there are provided on the table 11all of the aperture-grill supporting means 13, the aperture-grillpositioning means 17A, 17B, and the spring positioning means 19 whichare used upon two operations or more of the operation of measuring thepositions of the measurement positions Z₀ to Z₄ of the grill 107, theoperation of supplying the springs 3 to the respective springpositioning means 19, and the operation of welding the springs 3 to thespring holders 111. Therefore, it is not necessary to independentlyprovide the above-mentioned means 13, 17A, 17B, 19 at the spring supplyposition 901, the spring welding position 903 and the aperture-grilldelivery position 905 on the base mount 9, respectively. It is possibleto form the respective means 13, 17, 19 integrally, and hence it ispossible to simplify the arrangement of the welding apparatus 7.

Since all of the aperture-grill supporting means 13, the aperture-grillpositioning means 17A, 17B, and the spring positioning means 19 areprovided on the table 11, when the table 11 is moved to the positions901, 903, 905 while the respective means 13, 17A, 17B, 19 are beingoperated, it is possible to carry out the operation of measuring thepositions of the measurement positions Z₀ to Z₄ of the grill 107 and theoperation of supplying the springs 3 to the respective springpositioning means 19 with the aperture grill 1 being kept in a certainposture. It is also possible to carry out the operation of welding thesprings 3 to the spring holders 111 with the aperture grill 1 and thesprings 3 being kept in their certain postures.

Accordingly, it is possible to prevent the positions of the aperturegrill 1 or the springs 3 during the respective operations from beingchanged and hence it is possible to precisely weld the springs 3 topredetermined positions of the spring holders 111.

While in this embodiment the three supporting bodies 1301 respectivelysupport the upper lateral member 103 of the aperture grill 1 at oneposition and the lower lateral member 103 thereof at two positions, thepositions of the aperture grill 1 at which the supporting bodies 1301support the aperture grill are not limited to those described in theembodiment, e.g., the three supporting bodies 1301 may respectivelysupport the upper lateral member 103 at two positions and the lowerlateral member 103 at one position, or the three supporting bodies 1301may respectively support one member 105 of the left longitudinal member105 and the right longitudinal member 105 at one position and the othermember 105 at two positions.

While in the embodiment the aperture-grill supporting means 13 consistsof the three supporting bodies 1301, the arrangement of theaperture-grill supporting means 13 is not limited to the arrangementdescribed in the embodiment and may be selected optionally; theaperture-grill supporting means 13 may consist of a plurality ofarticulated arms provided on the table 11 and chucks provided at headends of the respective articulated arms for gripping proper positions ofthe left and right longitudinal members 105.

While in the embodiment the aperture grill 1 is supported with the frontsurface of the grill 107 being faced to the table 11 side, the aperturegrill 1 may be supported with the rear surface of the grill 107 beingfaced to the table 11 side.

While in the embodiment the table 11 is moved on the base mount 9 to thespring supply position 901, the spring welding position 903 and theaperture-grill delivery position 905, the operation of delivering andconveying the aperture grill 1 to and from the table 11, the operationof supplying the springs 3 to the respective spring positioning means19, and the operation of welding the springs 3 to the aperture grill 1may be carried out optionally at the same position or differentpositions on the base mount 9, for example, with such an arrangementthat the table 11 is fixed and the spring supplying means 21 and thespring welding means 23 are provided movably or the like.

Further, while in the embodiment the five grill-position measuring means15 measure the positions of the five measurement positions Z₀ to Z₄ atthe substantial center position of the front surface of the grill 107and the positions to the four corners thereof, the positions of themeasurement positions of the grill 107 and the number of the abovemeasurement positions and the grill-position measuring means 15 are notlimited to those described in the embodiment and may be selectedoptionally.

While in the embodiment the aperture grill 1 is conveyed onto the table11 after the springs 3 are supplied to the spring positioning means 19,the springs 3 may be supplied to the spring positioning means 19 afterthe aperture grill 1 is conveyed onto the table 11, for example, and itmay optionally be selected which of the aperture grill 1 and the springs3 are first conveyed onto the table 11.

Further, while in the embodiment there is described the case where thenumber of the pins 505 of the panel 5 and the number of the springs 3welded to the aperture grill 1 are respectively three, the presentinvention can be applied to the case where the number of the pins 505 ofthe panel 5 and the number of the springs 3 welded to the aperture grill1 are respectively four.

Subsequently, there will be described an embodiment in the case wherethe number of the pins and the number of the springs welded to theaperture grill are respectively four. Specifically, a method of and anapparatus for welding four springs simultaneously will be described.

FIGS. 10 and 11 show an aperture grill 21 to which the embodiment isapplied, and a panel 22 for supporting the aperture grill 21. In FIGS.10 and 11, parts corresponding to those shown in FIGS. 1 and 2 aremarked with the same reference numerals and hence need not be described.

The aperture grill 21 is arranged such that a sheet-shaped grill 107through which a plurality of slits 10 are formed is stretched at asubstantially rectangular frame 101 formed of upper and lower lateralmembers 103 and left and right longitudinal members 105 similarly to theabove-mentioned aperture grill, and that four panel attachment springs 33A, 3B, 3C, 3D! are respectively welded through spring holders 111 tofour positions on outer surfaces of the upper and lower lateral members103 and the left and right longitudinal members 105. A panel 22 includesa substantially rectangular panel portion 501 and four skirt portions503 projectingly formed from four sides of the panel portion 501similarly to the above-mentioned panel, being arranged such that pins(so-called panel pins) 505 505A, 505B, 505C, 505D! which can be engagedwith pin apertures 307 of the above corresponding springs 3 3A, 3B, 3C,3D! are fitted to inner surfaces of the four skirt portions 503. Theabove aperture grill 21 is attached to the panel 22 by welding baseportions 303 of the respective springs 3A to 3D to the spring holders111 to engage the pin apertures 305 of the respective springs 3A to 3Dwith the corresponding pins 505A to 505D of the panel 22 as shown inFIGS. 12 and 13. Thus, the aperture grill 21 is supported at the insideof the panel 22.

FIGS. 14 and 15 are respectively a plan view and a front view of awelding apparatus according to this embodiment. FIG. 16 shows a planview of a table provided in the welding apparatus. A welding apparatus24 includes a base mount 25 having a long size in the left and rightdirection and a rectangular shape when it is seen from its top side, atable 26 which is movably disposed on the base mount 25 and to which theaperture grill 21 is delivered, an aperture-grill supporting means 28provided on the table 26, a grill-position measuring means 29, left andright and upper and lower aperture-grill positioning means 30, 31, aspring positioning means 32, a spring welding means 33 for welding thesprings 3 positioned by the spring positioning means 32 to the aperturegrill 21, etc.

As shown in FIGS. 14 and 15, the table 26 is moved by a table drivemeans, not shown, provided on the base mount 25 in the left and rightdirections among a spring supply position 2501 located at a position toa left end of the base mount 25, a spring welding position 2503 to aright end of the base mount 25, and an aperture-grill delivery position2505 located at the middle of both positions. At the aperture-grillsupply position 2501, the springs 3 are supplied to the respectivespring positioning means 32 on the table 26 from a spring supplyportion. At the aperture-grill delivery position 2502, the aperturegrill 21 is delivered onto the table 26 with a front surface of thegrill 107 being faced toward the table 26.

Three aperture-grill supporting means 28 are provided. Each of theaperture-grill supporting means 28 includes a supporting body 2801 (aso-called bearer) supported by the table 26 so as to be capable of beinglifted up and down. Each of the aperture-grill supporting means isarranged such that, in a state that the aperture grill 21 is deliveredonto the table 26, the respective supporting bodies 2801 support theaperture grill at the front position, which is located at a substantialmiddle in the left and right direction, of the upper lateral member 103and two front positions, which are located at an interval in the leftand right direction, of the lower lateral member 103. Further, incorrespondence with the respective supporting bodies 2801, there areprovided press arms 34 for pressing the aperture grill 21 from positionsabove the upper and lower members 103 supported by the supporting bodies2801, i.e., from rear surface positions to fix the aperture grill 21 atthe positions (see FIGS. 16, 18 and 19).

The supporting bodies 2801 are lifted up and down by the lifting anddriving units (not shown) provided between the table 26 and thesupporting bodies 2801. The supporting bodies 2801 are lifted up anddown by the lifting and driving units under the control of a controlmeans, not shown, (e.g., a microcomputer) based on a measured result ofthe grill-position measuring means 29. In this embodiment, the liftingand driving unit and the control means form an aperture-grill postureadjusting means.

As shown in FIG. 18, at a position shown by a chain line, the press arm34 is brought away from the aperture grill 21 and brought in its standbystate. At a position shown by a real line, the press arm presses theupper and lower lateral members 103.

As shown in FIG. 16, the five grill-position measuring means 29 areprovided with corresponding to a measurement position Z₀ at asubstantial center of the front of the grill 107 of the aperture grill21 supported by the three supporting bodies 2801, and measurementpositions Z₁ to Z₄ located to four-corner sides thereof. Thegrill-position measuring means 29 can employ an arrangement similar tothat shown in FIG. 6, for example. The grill-position measuring means 29are arranged such that respective measuring points 2901 thereof arebrought in contact with the five measurement positions Z₀ to Z₄ of thegrill 107 of the aperture grill 21 supported by the three supportingbodies 2801, thereby the positions of the measurement positions Z₀ to Z₄being measured, and then the measured results are output to the aboveaperture-grill posture adjusting means.

As shown in FIG. 16, the left and right aperture-grill positioning means30 are respectively disposed on outer sides of the left and rightlongitudinal members 105, and the upper and lower aperture-grillpositioning means 31 are respectively disposed on outer sides of theupper and lower lateral members 103. As shown in FIG. 17, each of theleft and right aperture-grill positioning means 30 includes apositioning roller 3001 for being engaged with and released from each ofsubstantially middle outer side surface positions of the left and rightlongitudinal members 105, and a slider 3003 which supports the roller3001 and is movably supported by the table 26 through a guide rail 3002in the left and right direction, i.e., the direction X. Each of the leftand right aperture-grill positioning means is arranged such that aparting mechanism 3004 provided between both of the sliders 3003 andformed of a drive shaft 3006 and symmetrical links 3007 with respect tothe left and right direction permits the left and right positioningrollers 3001 to be respectively engaged with and released from the leftand right longitudinal members 105 of the aperture grill 21 insynchronization with each other.

As shown in FIG. 17, the respective upper and lower aperture-grillpositioning means 31 include two positioning rollers 3101 for beingengaged with and released from two outside positions, which are locatedat an interval in the left and right direction, of the upper lateralmember 103, and two positioning contact members 3102 for beingrespectively engaged with and released from two outer side surfacepositions, which are located at an interval in the left and rightdirection, of the lower lateral member 103. The two lower positioningrollers 3101 are supported by left and right ends of a rocking arm 3105which can be rocked around a supporting shaft 3104. The supporting shaft3104 is engaged with a long aperture 3106 which is a guide extended inthe upward and downward direction, i.e., the Y direction.

The two positioning contact members 3102 are supported on a commonsupporting plate 3107 disposed movably in the upward and downwarddirection (i.e., the Y direction). A parting mechanism 3110 formed of adrive shaft 3108 and links 3109 which are symmetrical in the upward anddownward direction and provided between the rocking arm 3105 and thecommon supporting plate 3107 permits the positioning rollers 3101 andthe positioning contact members 3102 to be engaged with and releasedfrom the upper and lower lateral members 103 in synchronization witheach other. Even if the frame 101 is twisted, the rocking of the rockingarm 3105 allows the positioning rollers 3101 and the positioning contactmembers 3102 to be reliably engaged with the upper and lower lateralmembers 103, thereby the aperture grill 21 being able to be positioned.

The four spring positioning means 32 are provided. As shown in FIGS. 16and 19, first, second, third and fourth spring positioning means 32A,32B, 32C, 32D are respectively provided outside the upper and lowerlateral members 103 and the left and right longitudinal members 105 ofthe aperture grill 21. As shown in FIGS. 14 and 15, each of the springpositioning means 32 32A, 32B, 32C, 32D! is supported by the table 26.

The spring positioning means 32 32A, 32B, 32C, 32D! respectively includeholding members for holding the springs 3 3A, 3B, 3C, 3D! similarly tothe above-mentioned spring positioning means. Similarly to theabove-mentioned holding members, the respective holding members includepins (so-called spring pins) 3201 3201A, 3201B, 3201C, 3201D! which canbe inserted into the pin apertures 307 of the springs 3 3A, 3B, 3C, 3D!,magnets for fitting outer surfaces of the head portions 305 of thesprings 3 3A, 3B, 3C, 3D! thereto with the spring pins 3201 beinginserted into the pin apertures 307, and two projections for preventingthe springs 3 from being rotated.

As shown in FIG. 19, the second and third spring positioning means 32B,32C are arranged such that their spring pins 3201B, 3201C can be movedonly in the left and right direction, i.e., in the X direction. Thefirst spring positioning means 32A is arranged such that its spring pin3201A can be moved in the left and right direction, i.e., the Xdirection and in the upward and downward direction, i.e., the Ydirection. The fourth spring positioning means 32D is arranged such thatits spring pin 3201D can be moved in the X direction, the Y direction,and the Z direction perpendicular to a plane of a sheet of the paper.

Each of the spring positioning means 32 32A, 32B, 32C, 32D! can be movedin the direction in which it is moved closer to and away from theaperture grill 21.

As shown in FIGS. 14 and 15, the spring welding means 33 includes asupporting frame 36 provided at the right end of the base mount 25 so asto stand, and a welding machine 37 supported by the supporting frame 36so as to be lifted up and down. The welding machine 37 includes fourwelding units 3701 3701D, 3701A, 3701C, 3701B! respectively used for theupper lateral member 103, the lower lateral member 103, the leftlongitudinal member 105, and the right longitudinal member 105. Each ofthe welding units 3701A to 3701D includes two electrode portionsdisposed so as to be opposed to each other and so as to be moved closeto and away from each other. In a state that the welding machine 33 islifted down by the lifting and driving mechanism, the respectiveelectrode portions are opposed to the inner surface of the spring holder111 and the outer surface of the base portion 303 of the spring 3. Therespective electrode portions are brought close to each other so as tobe brought in contact with the spring holder 111 and the spring 3 andthen energized, thereby the spring holder 111 and the spring 3 beingwelded by the spot welding.

It will be described to simultaneously weld the four springs 3 3A, 3B,3C, 3D! to the corresponding spring holders 111 by using the weldingapparatus 24.

At first, at the spring supply position 2501, the springs 3 3A, 3B, 3C,3D! are respectively supplied to the spring pins 3201 3201A, 3201B,3201C, 3201D! of the spring positioning means 32 32A, 32B, 32C, 32D! onthe table 26 and then held.

Then, the table drive means moves the table 26 to the aperture-grilldelivery position 2502, where the respective lifting and driving unitsof the aperture-grill supporting means 28 locate the head ends of thethree supporting bodies 2801 at the reference positions whose heightsfrom the table 26 are the same. In this state, the conveying meansmounts the aperture grill 21 on the three supporting bodies 2801.

The aperture-grill positioning means 30 and 31 position the aperturegrill 21 from the X direction and the Y direction with reference to thepositions of the spring pins 3201B and 3201C of the second and thirdspring positioning means 32B and 32C, and then fixed by the press arms34 with respect to the Z direction in the positioned state (see FIG.19).

Five measuring points 2901 of the grill-position measuring means 29 arerespectively brought in contact with five measurement positions Z₀ to Z₄of the grill 107 of the aperture grill 21, thereby measuring sizes PGHPGH₀, PGH₁, PGH₂, PGH₃, PGH₄ ! from a reference plane 39 to the outersurfaces of the grill 107 which are determined by the first, second andthird spring pins 3201A, 3201B and 3201C (see FIG. 20). Though notshown, when the panel 22 is positioned, sizes PPH PPH₀, PPH₁, PPH₂,PPH₃, PPH₄ ! from the reference plane to the panel inner surface whichare determined by the three panel pins 505A, 505B and 505C are similarlymeasured at measurement positions corresponding to the measurementpositions Z₀ to Z₄ of the aperture grill 21. Based on these measuredvalues PGH and PPH, the interval GH between the inner surface of thepanel 22 and the grill 107 of the aperture grill 21 is measured (seeFIG. 13).

The press arms 34, the respective positioning rollers 3001, 3101 of theaperture-grill positioning means 30 and 31, the positioning contactmembers 3102 thereof and so on are moved away from the aperture grill 21to release the positioning of the aperture grill 21. Thereafter, underthe control of the above-mentioned control means, the lifting anddriving unit is operated to lift the three supporting bodies 2801 up anddown and the posture of the aperture grill 21 is adjusted so that theinterval GH should be set to the standard size. Specifically, theposition of the aperture grill 21 in the Z direction is determined.

Thus, the interval GH (see FIG. 13) between the panel inner surface andthe grill 107 of the aperture grill 21 is set and the interval GHmarriage is finished. The aperture grill is positioned again by theaperture-grill positioning means 30 and 31 and the press arms 34.

Subsequently, a so-called engagement marriage which is the positioningof the springs 3 3A, 3B, 3C, 3D! is carried out. The springs 3A to 3Dare respectively positioned and held by the spring pins 3201A to 3201D.As shown in FIG. 12, the respective positions (ax, ay, bx, cx, dx, dy,dz) of the panel pins 505A to 505D are measured simultaneously with themeasurement of the sizes PPH from the reference plane to the panel innersurface (see FIG. 13).

The second and third spring positioning means 32B, 32C are moved so thatreference X-direction positions (BX, CX) of the second and third springpins 3201B and 3201C should be agreed with X-direction positions (bx,cx) of the second and third panel pins 505B and 505C BX=bx, CX=cx!.

With reference to the positions of the second and third spring pins3201B and 3201C, the first spring positioning means 32A is moved so thatX- and Y-direction positions (AX, AY) of the first spring pin 3201Ashould be agreed with X- and Y-direction positions (ax, ay) of the firstpanel pins 505A.

Further, the fourth spring positioning means 32D is moved so that X-, Y-and Z-direction positions (DX, DY, DZ) of the fourth spring pin 3201Dshould be agreed with X-, Y- and Z-direction positions (dx, dy, dz) ofthe fourth panel pin 505D relative to the positions of the first, secondand third spring pins 3201A, 3201B and 3201C.

Thus, relative positions of the panel pins 505 and the spring pins 3201(accordingly the pin apertures of the springs engaged with the springpins 3201 respectively) are agreed with each other and the engagementmarriage is finished.

In this state, the respective base portions 303 of the springs 3A to 3Dsupported by the spring pins 3201A to 3201D are brought in contact withthe corresponding spring holders 111. Upon the engagement marriage,since the first, second and third spring pins 3201A, 3201B and 3201C areprevented from being moved in the Z direction, the interval GH marriageis prevented from being changed.

The table drive means moves the table 26 to the spring welding position2503, where the welding machine 37 of the spring welding means 33 islifted down. The four welding units 3701A to 3701D simultaneously weldthe base portions 303 of the springs 3A to 3D to the spring holders 111,respectively.

After welding the springs, the welding machine 37 is lifted up. Thetable drive means moves the table 26 to the aperture-grill deliveryposition 2502. The spring positioning means 32A to 32D are moved in thedirection in which they are moved away from the aperture grill 21,thereby the spring pins 3201A to 3201D being pulled out of the pinapertures 307 of the springs 3A to 3D. The press arms 34 and the springpositioning means 30 and 31 are moved away from the aperture grill 21 torelease the positioning of the aperture grill 21. Then, the conveyingmeans conveys the aperture grill 21 from the table 26.

According to this embodiment, when the four springs 3A to 3D are weldedto the aperture grill 21 in the case of a high-definition CRT, forexample, it is possible to weld the four springs 3A to 3D to the fourpositions of the upper and lower lateral members 103 and the left andright longitudinal members 105 simultaneously. Therefore, an error inthe positioning of the aperture grill 21 and the springs 3A to 3D isreduced, which can improve quality of the CRT.

According to this embodiment, since the so-called interval GH marriagefor setting the interval GH between the aperture grill and the panel andthe so-called engagement marriage for agreeing the pin aperturepositions of the four springs with the four panel pin positions of thepanel are carried out on the same table, the welding which has beencarried out in two processes is completed only in one process, whichimproves the working property. An equipment for the interval GH marriageand an equipment for the engagement marriage are made integral, whichcan improve efficiency in a space of the equipment.

The embodiment for simultaneously welding the four springs, similarly tothe above embodiment for simultaneously welding the three springs, canbe modified. For example, the positions of the aperture grill 21supported by the three supporting bodies 2801 are not limited to thepositions described in the embodiment. The aperture grill 21 may besupported by, for example, an arrangement in which the aperture grill issupported with the rear surface of the grill 107 being faced toward thetable 26. The number of the grill-position measuring means 29 and themeasurement positions are not limited to that described in theembodiment and hence may be selected optionally. Further, it may beoptionally selected which of the aperture grill 21 and the springs 3 aresupplied onto the table 26 first.

We claim:
 1. A method of welding a spring to an aperture grill, whereinpanel attachment springs are welded to at least three side portions offour side portions of a substantially rectangular aperture grill havinga color selection grill, said method comprisingdisposing said aperturegrill so that said selection grill is opposed to a predeterminedreference plane; disposing said springs at positions opposed to said atleast three side portions outside said aperture grill on a planesubstantially parallel to said reference plane; measuring a plurality ofmeasurement positions of said selection grill relative to said referenceplane; adjusting a posture of said aperture grill based on measuredresults of the respective measurement positions of said selection grillso that said respective measurement positions is located at referencepositions relative to said reference plane; after a posture of saidaperture grill is adjusted, moving said springs close to said aperturegrill on a plane parallel to said reference plane; and contacting andwelding said springs in contact with and to said at least three sideportions.
 2. A method of welding a spring to an aperture grill accordingto claim 1, characterized in that three supporting bodies respectivelysupport one side portion of a pair of said side portions opposed to eachother at a middle side-portion position in the extended direction ofsaid side portion and the other side portion at two side-portionpositions located at an interval in the extended direction of said sideportion and said respective supporting bodies are moved close to onesaid side portion and away from the other said side portion, thereby theposture of said aperture grill being adjusted.
 3. A method of welding aspring to an aperture grill according to claim 1, characterized in thatmeasurement of positions of a plurality of measurement positions of saidselection grill with respect to said reference plane and the welding ofsaid springs to said at least three side portions are respectivelycarried out at positions located at an interval along said referenceplane.
 4. A spring welding apparatus for welding panel attachmentsprings to at least three side portions of a substantially rectangularaperture grill having a color selection grilla table; an aperture-grillsupporting means for supporting said aperture grill on said table sothat a posture of the former can be adjusted; a grill-position measuringmeans for measuring a plurality of measurement positions of saidselection grill in a state that said aperture-grill supporting meanssupports said aperture grill; an aperture-grill posture adjusting meansfor driving said aperture-grill supporting means based on measurementobtained by said grill-position measuring means and for adjusting theposture of said aperture grill so that the plurality of measurementpositions of said selection grill should be located at respectivepredetermined positions; an aperture-grill positioning means forpositioning on said table said aperture grill adjusted in posture bysaid aperture-grill posture adjusting means; a spring positioning meansdisposed at positions opposed to said at least three side portions ofsaid aperture grill positioned by said aperture-grill positioning means,for bringing said springs in contact with said at least three sideportions to position the former; and a spring welding means for weldingthe springs positioned by said spring positioning means to the sideportions of said aperture grill positioned by said aperture-grillpositioning means.
 5. A spring welding apparatus according to claim 4,wherein said aperture-grill supporting means comprises three supportingbodies for respectively supporting one side portion of said sideportions, which are provided in said table so that they can be lifted upand down and which are opposed to each other, at a middle side-portionposition in the extended direction of said side portion and the otherside portion at two side-portion positions located at an interval in theextended direction of said side portion, and said aperture-grill postureadjusting means comprises a lifting and driving source for lifting saidrespective bodies up and down.
 6. A spring welding apparatus accordingto claim 4, wherein said aperture-grill supporting means, saidgrill-position measuring means, said aperture-grill posture adjustingmeans, said aperture-grill positioning means, and said springpositioning means are provided in said table.
 7. A spring weldingapparatus according to claim 4, further comprising a spring supplyingmeans for supplying springs to said respective spring positioning means.8. A spring welding apparatus according to claim 7, further comprising abase mount for movably supporting said table and a table drive means formoving said table on said base mount, wherein measurement of positionsof the plurality of measurement positions of said selection grill bysaid grill-position measuring means, supply of springs to saidrespective spring positioning means by said spring supplying means, andthe welding of said springs to said aperture grill by said springwelding means are carried out in a state that said table is moved todifferent positions on said base mount.
 9. A spring welding apparatusaccording to claim 4, wherein the side portion of said aperture grillcomprises four upper, lower, left and right members, spring holders areattached to at least three members of said four members, and said springwelding means welds said springs to said spring holders.
 10. A method ofwelding a spring to an aperture grill, wherein panel attachment springsare welded to four side portions of a substantially rectangular aperturegrill having a color selection grill, said method comprising:disposingsaid springs at first, second, third, and fourth spring pins with fourspring positioning means for positioning said springs; disposing saidaperture grill so that said selection grill is opposed to a referenceplane determined by the spring pins of three spring positioning means ofsaid four spring positioning means; measuring a plurality of measurementpositions of said selection grill relative to said reference plane;adjusting a posture of said aperture grill based on the respectivemeasurement positions of said selection grill so that said respectivemeasurement positions are located at predetermined reference positionsrelative to said reference plane; matching positions of the respectivespring pins of said four spring positioning means with positions ofpanel pins provided on four side portions of a panel of a cathode-raytube; and welding said four springs to the four side portions of saidaperture grill simultaneously.
 11. A method of welding a spring to anaperture grill according to claim 10, wherein the second and thirdspring pins are opposed to each other in a first direction and are movedso that first-direction positions of said second and third spring pinsare matched with positions of corresponding second and third panel pins,opposed to each other in the first direction of said panel pins,thefirst spring pin, which is one of spring pins opposed to each other inthe second direction perpendicular to the first direction, is moved sothat the first-direction position and second-direction position of saidfirst spring pin are matched with a position of a first panel pin whichis one of panel pins opposed to each other in the second direction, anda fourth spring pin in the second direction is moved so that first-,second-, and third-direction positions, which are perpendicular to oneanother, of said fourth spring pin are matched with a position of afourth panel pin.
 12. A spring welding apparatus for welding panelattachment springs to four side portions of a substantially rectangularaperture grill having a color selection grilla table; an aperture-grillsupporting means for supporting said aperture grill on said table at atleast three positions so that a posture of the former can be adjusted; agrill-position measuring means for measuring of a plurality ofmeasurement positions of said selection grill in a state that saidaperture-grill supporting means supports said aperture grill; anaperture-grill posture adjusting means for adjusting said aperture-grillsupporting means based on measurements obtained by said grill-positionmeasuring means and for adjusting a posture of said aperture grill sothat a plurality of measurement positions of said selection grill arelocated at corresponding predetermined positions; an aperture-grillpositioning means for positioning on said table said aperture grill at aposture adjusted by said aperture-grill posture adjusting means; first,second, third and fourth spring positioning means disposed at positionsopposed to the four side portions of said aperture grill positioned bysaid aperture-grill positioning means, for contacting said springs withsaid four side portions; and a spring welding means for welding thesprings positioned by said spring positioning means to the side portionswherein of said four spring positioning means, said second and thirdspring positioning means are opposed to each other in a first directionand can be moved and adjusted in the first direction, a first springpositioning means in a second direction perpendicular to the firstdirection can be moved and adjusted in the first and second directions,and said fourth spring positioning means in the second direction can bemoved and adjusted in the first, second and third directions.